The present invention relates to the cleaning of etchant residues formed in the etching of substrates.
When an energized gas is used to process a substrate in a chamber, for example to etch the substrate, etchant residues are often deposited on internal surfaces of the chamber. The deposited etchant residues may adversely affect the substrate processing operations conducted in the chamber. For example, the etchant residues can corrode the surfaces of the chamber and its internal components, requiring frequent replacement of the components, and thereby increasing chamber downtime. The accumulated etchant residues can also flake off from the chamber surfaces and contaminate substrates being etched in the chamber. Thus, the etchant residues needs to be periodically cleaned off the chamber surfaces.
In conventional cleaning processes, a cleaning gas energized by RF or microwave energy is provided in the chamber to clean the etchant residues. The cleaning gas composition and other process parameters are tailored to clean the particular etchant residue composition that is generated during the etching process. For example, a conventional cleaning process to clean a chamber having silicon containing etchant residues that are generated by the etching of silicon containing substrate material in the chamber, may use a cleaning gas composition tailored to clean the silicon containing etchant residues.
However, conventional cleaning processes are generally not very efficient at cleaning etchant residues composed of multiple layers having different chemical compositions, such as those generated in foundry etching processes. In foundry etching, the same chamber is often used to etch a number of different types of substrate materials, thereby often generating layers of etchant residues having a variety of different types of compositions which deposit upon one another on the surfaces in the chamber. Conventional cleaning processes do not efficiently clean these multi-layer etchant residues because they are tailored to clean the single composition etching residues formed in a simpler etching process. Thus, when conventional cleaning process are used to clean foundry etch chambers, the chamber is often cleaned non-uniformly because the cleaning gas is more effective at cleaning certain compositions of etchant residues. The conventional cleaning process can also result in overcleaning and resultant erosion of the foundry etch chamber.
Thus, it is desirable to have a cleaning process capable of cleaning a chamber after the etching of a number of different types of substrates in the chamber. It is further desirable to have a cleaning process capable of cleaning multi-layer etchant residues without excessive erosion of the underlying chamber surfaces.